syncpack vs npm-check: Should You Switch? 491ms vs 1.5s

On a 12-package npm workspaces fixture (13 package.json files) with planted version drift, syncpack 15.3.3 lint finished in a median 491 ms offline and exited 1 with 21 mismatch lines. npm-check 6.0.1 --skip-unused took a median 1.54 s at the repo root and 1.59 s on packages/web, because it hits the npm registry for outdated versions.

Short answer: use syncpack when the question is "are our workspace versions consistent?" Use npm-check when the question is "what installed packages are outdated or unused?" They are not drop-in replacements. No affiliate links in this post.

What I tested

• Machine: 8 vCPU Intel Xeon / 15 GB RAM Linux cloud box, Node 20.19.2 / npm 9.2.0, tested 5 Oct 2026 (about 23:30 to 23:32 IST). Shared box; variants timed after warmups.
• Fixture: /workspace/bench-syncpack-npm-check/ — root workspaces monorepo with 12 packages under packages/* (web, admin, api, worker, cli, ui, auth, billing, search, notify, analytics, shared). Shared deps intentionally drifted (axios, lodash, zod, react, typescript, eslint, prettier).
• Tools: syncpack 15.3.3, npm-check 6.0.1. Root also had those tools installed so npx resolved locally.
• Timing: seven npx syncpack lint runs; three npx npm-check --skip-unused --no-emoji runs at repo root; three on packages/web. Wall clock via process.hrtime around the full command.
• Findings: syncpack lint median 490.9 ms (469 / 477 / 482 / 491 / 491 / 492 / 492), exit 1, 21 ✘ lines across axios/eslint/lodash/prettier/react/typescript/zod. npm-check root median 1542.3 ms (1436 / 1542 / 1598). npm-check packages/web median 1590.2 ms (1554 / 1590 / 1944).
• One surprise: npm-check on a workspace package still needs network and reports major upgrades (for example React 18 to 19); it does not list cross-package semver drift the way syncpack does.
• Not tested: syncpack fix / syncpack update, npm-check -u interactive mode, pnpm/yarn catalogs, unused-dep accuracy across TypeScript path aliases, Windows/macOS.

Is syncpack faster than npm-check?

Variant	Median wall	Runs (ms)	Network
syncpack 15.3 lint (13 package.json)	491 ms	469 / 477 / 482 / 491 / 491 / 492 / 492	no
npm-check 6.0 root --skip-unused	1542 ms	1436 / 1542 / 1598	yes
npm-check 6.0 packages/web --skip-unused	1590 ms	1554 / 1590 / 1944	yes

Yes for a CI consistency gate. syncpack only reads package.json files and compares version strings, so it stays under half a second here. npm-check asks registries what is current, so it is slower and the result changes when the registry moves. If you ran npm-check once per workspace package, twelve packages would be tens of seconds before you even fixed anything.

Package-manager choice is a separate decision. The pnpm vs npm vs bun post covers installers; the turbo vs nx post covers monorepo task graphs. This post only covers dependency version hygiene CLIs.

What does each tool actually catch?

Job	syncpack lint	npm-check
Same dependency, different versions across packages	Yes (21 mismatches here)	No
Outdated vs latest on the registry	Not in this lint run	Yes
Unused dependencies	No	Yes (skipped here with --skip-unused)
Works without installing workspace node_modules	Yes	Weak / misleading without installs
CI-friendly non-interactive fail	Exit 1 on mismatches	Report only unless you script it

On this fixture syncpack flagged axios, eslint, lodash, prettier, react, typescript, and zod drift, including exact 4.17.21 vs caret ^4.17.21 lodash rows. npm-check at root reported major upgrades for eslint and typescript among the installed tool tree. On packages/web it reported React, zod, typescript, eslint, and prettier upgrades. Different signals.

If your pain is "why does CI resolve two lodashes?", start with syncpack. If your pain is "what can we bump this month?", start with npm-check or npm-check-updates. The knip vs depcheck post covers unused-export detection, which overlaps npm-check's unused mode but not syncpack.

Should you switch from npm-check to syncpack?

Situation	My pick
npm workspaces / pnpm / yarn monorepo with version drift	Add syncpack lint to CI; keep an outdated tool separately
Single package.json app	syncpack adds little; keep npm-check or ncu
You only want interactive "what should I bump"	Stay on npm-check (-u) or use npm-check-updates
You need workspace: / catalog rules enforced	syncpack
You refuse network in CI dependency gates	syncpack lint

Bottom line: on 12 workspace packages, syncpack lint was about 491 ms offline with 21 actionable mismatches; npm-check was about 1.5 s per target and answered a different question. Who should not "switch": anyone treating these as the same tool — replace nothing, compose them. For TypeScript upgrade timing on the same box, see the TypeScript 7 upgrade post.

How this was made: I generated the 12-package fixture with planted drift, ran syncpack lint and npm-check on the ShopperCove test box, and kept the timing JSON; the write-up was drafted with AI help and checked against that output.

Sources

• 01syncpack.devhttps://syncpack.dev/
• 02github.com/JamieMason/syncpack
• 03npmjs.com/package/syncpack
• 04npmjs.com/package/npm-check
• 05github.com/dylang/npm-check
• 06docs.npmjs.com/cli/v10/using-npm/workspaces

Related

• 01shoppercove.com/blog/madge-vs-dependency-cruiser
• 02shoppercove.com/blog/nodejs-26-lts-october-2026-schedule-change
• 03shoppercove.com/blog/lefthook-vs-husky
• 04shoppercove.com/blog/oxlint-vs-eslint